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<html xmlns="http://www.w3.org/1999/xhtml" lang="zh-CN">
<head>
<title>检索字符出现次数</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="description" content="" />
<meta name="keywords" content="" />
<script type="text/javascript">
    var str = '2340sadfja2affa2';
    str = str.split('');
    var n = 0;
    for(var i=0; i<str.length; i++) {
        if(str[i] == 'a') {
            n++;
        }
    }
    document.write('共出现' + n + '次');
</script>

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</style>
</head>
    <body>
    </body>
</html>